High-LET-induced chromosome aberrations in V79 cells analysed in first and second post-irradiation metaphases

PURPOSE

As an extension of previous studies, the time-course of high-LET-induced chromosomal damage was investigated in first- and second-cycle V79 Chinese hamster cells.

MATERIALS AND METHODS

Cells were exposed in G1 to 10.4 MeV/u Ar ions (LET = 1226 keV/microm) and chromosomal damage was measured at 2h sampling intervals between 10 h and 34 h after irradiation. To distinguish between cells in different post-irradiation cycles, the fluorescence-plus-Giemsa technique was applied.

RESULTS

For first- and second-generation cells, the number of aberrant metaphases and aberrations per metaphase were found to increase markedly with sampling time, demonstrating that cell cycle progression was delayed according to the number of lesions carried by the cell. To account for the time-dependent expression of chromosomal damage a mathematical approach was used based on the integrated flux of aberrant cells entering mitosis. Moreover, the analysis of Ar ion-induced chromosome lesions confirmed that high-LET radiation results in specific changes in the spectrum of aberration types. In particular, an increased rate of chromatid-type aberrations as well as a high frequency of chromosomal breaks was found, although the cells were exposed in G1.

CONCLUSIONS

Due to the fact that cells collected at one sampling time are not representative of the entire population, the complete time-course of chromosomal damage has to be taken into account for the determination of a meaningful RBE value. Otherwise, the analysis of chromosomal damage can result in a pronounced over- or underestimation of the RBE depending on the subpopulation of cells entering mitosis at that particular sampling time.

Can Doppler systemic venous flow indices predict central venous pressure in children?

Tricuspid valve, superior vena cava (SVC), and hepatic vein Doppler patterns may be abnormal in right heart anomalies and have been used to predict high central venous pressure (CVP) in adults. The purpose of this study was to evaluate the relationship of these systemic venous flow indices to CVP in children. Children undergoing cardiac catheterization were studied prospectively using simultaneous recordings of mean CVP with pulsed-Doppler tracings of SVC, hepatic vein, and tricuspid valve flow. Systemic venous Doppler measurements included peak velocities and velocity time integrals for ventricular systole (S), ventricular diastole (D), and ventricular systole (B), and atrial systole (A). Tricuspid inflow Doppler E and A waves were recorded also. Patients with significant tricuspid stenosis or regurgitation, systemic venous obstruction, and nonsinus rhythm were excluded. The 42 patients ranged in age from 0.2 to 21.0 years and in weight from 3.0 to 68.0 kg. Mean CVPs ranged from 1 to 17 mmHg. Catheterization indications included hemodynamic evaluation (25 patients), transplant biopsy, (11 patients), and interventional procedures (6 patients). No SVC or tricuspid valve Doppler measurement correlated with CVP. Hepatic vein peak D, peak B, and peak A significantly correlated with CVP (r = 0.34 - 0.55; P < 0.05, linear regression). For all correlations, the r values were low with significant overlap among patients. Thus, in children, only hepatic vein peak velocities correlate with CVP. Because of the low r values and significant overlap among patients, the currently used Doppler indices have a low sensitivity for predicting CVP in this age group.

Are screening echocardiograms warranted for neonates with meningomyelocele?

OBJECTIVE

To evaluate the incidence and types of congenital heart defects associated with meningomyelocele.

DESIGN

All neonates who underwent meningomyelocele repair and had a perioperative echocardiogram from July 1990 to October 1998 were studied. Medical records were reviewed for age, weight, clinical cardiac examination results, meningomyelocele location, and associated noncardiac defects. Heart defects were identified from reviewing echocardiographic reports and videotapes.

RESULTS

At meningomyelocele surgery, the 105 patients (53 female; 52 male) ranged in age from 1 to 20 days and in weight from 0.6 to 4.1 kg. Congenital heart disease was detected in 39 patients (37%). A secundum atrial septal defect was the most common defect (24%). A ventricular septal defect was found in 10 patients, 2 patients had anomalous pulmonary venous return, and 1 each had tetralogy of Fallot, bicuspid aortic valve, coarctation, and hypoplastic left heart syndrome. A patent ductus arteriosus and patent foramen ovale were not considered abnormal in these neonates. The cardiac examination was abnormal in only 5 of the 39 patients with heart defects (sensitivity = 13%). The presence of associated noncardiac defects (in addition to meningomyelocele) and location of the meningomyelocele (cervicothoracic vs lumbar) did not affect the incidence of heart disease. Of the patients with heart defects, girls were more frequently affected (25 of 39 vs 14 of 39, P<.05).

CONCLUSIONS

Congenital heart defects are common in neonates, especially girls, with meningomyelocele and are unrelated to meningomyelocele location or associated noncardiac defects. Because the clinical examination is insensitive for detecting heart defects in this group, screening echocardiograms are warranted. This information has important implications for ventriculoatrial shunting, urinary tract instrumentation (antibiotic prophylaxis), and neurosurgical procedures (venous air embolism).

RBE for carbon track-segment irradiation in cell lines of differing repair capacity

PURPOSE

The LET position of the RBE maximum and its dependence on the cellular repair capacity was determined for carbon ions. Hamster cell lines of differing repair capacity were irradiated with monoenergetic carbon ions. RBE values for cell inactivation at different survival levels were determined and the differences in the RBE-LET patterns were compared with the individual sensitivity to photon irradiation of the different cell lines.

MATERIAL AND METHODS

Three hamster cell lines, the wild-type cell lines V79 and CHO-K1 and the radiosensitive CHO mutant xrs5, were irradiated with carbon ions of different energies (2.4-266.4 MeV/u) and LET values (13.7-482.7 keV/microm) and inactivation data were measured in comparison to 250 kV x-rays.

RESULTS

For the repair-proficient cell lines a RBE maximum was found at LET values between 150 and 200 keV/microm. For the repair-deficient cell line the RBE failed to show a maximum and decreased continuously for LET values above 100 keV/microm.

CONCLUSIONS

The carbon RBE LET relationship for inactivation is shifted to higher LET values compared with protons and alpha-particles. RBE correlated with the repair capacity of the cells.

A national survey of practice nurse involvement in mental health interventions

BACKGROUND

The move in the United Kingdom (UK) from institutional to community care has led to an inevitable increase in the involvement of practice nurses (PNs) in mental health care. Around 20 000 PNs are currently working in the United Kingdom (UK). However, the extent and nature of PN involvement in delivering mental health interventions has not been adequately explored.

AIM

This study aimed to quantify practice nurses' involvement in delivering mental health interventions in primary care settings.

METHOD

A questionnaire was sent to a random sample of 1500 practice nurses registered with the Practice Nurse Forum at the Royal College of Nursing. Sixty per cent of questionnaires were returned; however, once non-eligible respondents were removed an adjusted response rate of 54% was achieved.

RESULTS

Practice nurses play a significant role in the assessment and treatment of mental health problems, most frequently via the administration of depot antipsychotics and the screening for depression. However, antipsychotic side-effects were infrequently monitored and PNs' understanding of treatment issues in depression is poor. These findings may be associated with the reported lack of mental health training that PNs have received.

CONCLUSIONS

The findings of this study have important implications for the training of practice nurses in mental health, specifically in the areas of medication management and the detection of mental disorders.

Pulmonary vein stenosis with normal connection: associated cardiac abnormalities and variable outcome

BACKGROUND

Pulmonary vein (PV) stenosis with anatomically normal connection is considered rare, unresponsive to treatment, progressive, and usually fatal.

METHODS

We reviewed the records of 13 children with this diagnosis at our center since 1990.

RESULTS

The number of stenosed PVs ranged from all PVs (n = 5); three PVs (n = 1); two PVs (n = 5); and one PV (n = 2). All patients had associated congenital cardiac abnormalities. Operation on PV stenosis was attempted in 7 patients (54%), 2 of whom have done well and 5 of whom have not. Two patients underwent heart transplantation for inoperable associated cardiac lesions. Significantly more patients with three or four stenosed PVs died (83%) compared with patients with one or two stenosed PVs (0%).

CONCLUSIONS

(1) Pulmonary vein stenosis with anatomically normal connection is associated with other congenital cardiac abnormalities, (2) presentation and outcome are contingent on the number of stenosed PVs, (3) surgical palliation may be helpful in some patients, and (4) heart transplantation for inoperable associated cardiac abnormalities may be an option in patients with only one or two stenosed PVs.

Crystal structure of a phycourobilin-containing phycoerythrin at 1.90-A resolution

The structure of R-phycoerythrin (R-PE) from the red alga Griffithsia monilis was solved at 1.90-A resolution by molecular replacement, using the atomic coordinates of cyanobacterial phycocyanin from Fremyella diplosiphon as a model. The crystallographic R factor for the final model is 17.5% (Rfree 22.7%) for reflections in the range 100-1.90 A. The model consists of an (alphabeta)2 dimer with an internal noncrystallographic dyad and a fragment of the gamma-polypeptide. The alpha-polypeptide (164 amino acid residues) has two covalently bound phycoerythrobilins at positions alpha82 and alpha139. The beta-polypeptide (177 residues) has two phycoerythrobilins bound to residues beta82 and beta158 and one phycourobilin covalently attached to rings A and D at residues beta50 and beta61, respectively. The electron density of the gamma-polypeptide is mostly averaged out by threefold crystallographic symmetry, but a dipeptide (Gly-Tyr) and one single Tyr could be modeled. These two tyrosine residues of the gamma-polypeptide are in close proximity to the phycoerythrobilins at position beta82 of two symmetry-related beta-polypeptides and are related by the same noncrystallographic dyad as the (alphabeta)2 dimer. Possible energy transfer pathways are discussed briefly.

Recording skills practice on videotape can enhance learning - a comparative study between nurse lecturers and nursing students

Video recording techniques have been used in educational settings for a number of years. They have included viewing video taped lessons, using whole videos or clips of tapes as a trigger for discussion, viewing video recordings to observe role models for practice, and being video recorded in order to receive feedback on performance from peers and tutors. Although this last application has been in use since the 1960s, it has only been evaluated as a teaching method with health care professionals in the past 10 years and mostly in the areas of medical and counsellor education. In nurse education, however, use of video recording techniques has been advocated without any empirical evidence on its efficacy. This study has used nursing degree students and nurse educationalists to categorize statements from four cohorts of students who took part in a 12-day clinical supervision course during which their interpersonal skills were recorded on videotape. There were two categories: positive and negative/neutral. Analysis of the data showed that between 61% and 72% of the subjects gave an overall positive categorization to the statements in the questionnaire. Chi-square tests were significant for all groups in both categories. This suggests that both nursing students and nurse lecturers thought that course participants' statements expressed a positive belief that video tape recording is useful in enhancing students' ability to learn effective interpersonal skills in clinical supervision.

2-Deoxy-D-glucose and mercaptoacetate induce different patterns of macronutrient ingestion

2-Deoxy-D-glucose (2DG) and mercaptoacetate (MA) are antimetabolic agents that reduce the metabolism of glucose and fatty acids, respectively, and stimulate feeding. The present study compared the effects of MA and 2DG on macronutrient self-selection. Because 2DG and MA have different metabolic actions and appear to activate different neural pathways, our hypothesis was that 2DG and MA would elicit different patterns of macronutrient selection. The first experiment examined macronutrient selection in response to 2DG, MA, and 0.9% saline in rats maintained on a three-macronutrient self-selection diet consisting of cornstarch, casein, and vegetable oil. Subsequently, one macronutrient source was replaced in each of three similar experiments with Polycose, albumin, or solid vegetable shortening. Finally, 2DG and MA tests were conducted in which only one macronutrient (cornstarch, casein, or oil) was available during the test. Results show that MA and 2DG elicit different macronutrient preferences. 2DG elicits intake of all three macronutrients in the same relative proportion consumed during spontaneous feeding across a number of dietary conditions, suggesting that glucoprivation activates interoceptive signals and neural pathways similar to those involved in normal hunger. MA elicits a selective intake of protein. Conditions in which carbohydrate palatability is enhanced or protein palatability is diminished lead to a relative increase in carbohydrate intake in response to MA. However, MA did not increase the intake of fat. Results suggest that intake of each macronutrient is subject to separate neural or endocrine control, and that these controls are linked to metabolic cues.

Septal cystic mass in the right atrium: echocardiographic evaluation

Right atrial masses rarely are seen in children and are usually benign. Clinical manifestations mainly depend on the location of the mass and whether it alters blood flow. This report describes the clinical course, echocardiographic findings, pathology, and serial follow-up of an unusual cystic mass with a mixture of tissue common to the atrioventricular septum located in the posteroinferior right atrium.

Subgroups of hindbrain catecholamine neurons are selectively activated by 2-deoxy-D-glucose induced metabolic challenge

Glucose is a major fuel for body energy metabolism and an essential metabolic fuel for the brain. Consequently, glucose deficit (glucoprivation) elicits a variety of physiological and behavioral responses crucial for survival. Previous work indicates an important role for brain catecholamine neurons in mediation of responses to glucoprivation. This experiment was conducted to identify the specific catecholamine neurons that are activated by glucoprivation. Activation of hindbrain catecholamine neurons by the antimetabolic glucose analogue, 2-deoxy-D-glucose (2DG; 50, 100, 200 or 400 mg/kg, s.c.) was evaluated using double label immunohistochemistry. Fos protein was used as the marker for neuronal activation and the enzymes tyrosine hydroxylase (TH) and phenethanolamine-N-methyl transferase (PNMT) were used as the markers for norepinephrine (NE) and epinephrine (E) neurons. 2-Deoxy-D-glucose (200 and 400 mg/kg) produced selective activation of distinct hindbrain catecholamine cell groups. In the ventrolateral medulla, doubly labeled neurons were concentrated in the area of A1/C1 and were predominantly adrenergic in phenotype. In the dorsal medulla, doubly labeled neurons were limited to C2 and C3 cell groups. In the pons, some A6 neurons were Fos-positive. Neurons in rostral C1, ventral C3, A2, A5 and A7 did not express Fos-ir in response to 2DG. Our results identify specific subpopulations of catecholamine neurons that are selectively activated by 2DG. Previously demonstrated connections of these subpopulations are consistent with their participation in the feeding and hyperglycemic response to glucoprivation. Finally, the predominant and seemingly preferential activation of epinephrine neurons suggests that they may play a unique role in the brain's response to glucose deficit.

Analysis of chromosome damage based on the time course of aberrations

PURPOSE

To describe a method for the analysis of radiation induced chromosome aberrations which will in particular be suitable for the comparison of different radiation qualities. The method is applied to previously published data.

METHODS

The basic idea of the approach is to use the time-course of aberrations up to the time when all cells have passed through first mitosis. Instead of comparing data obtained at a single sampling time, the number of aberrant cells or aberrations is integrated over several sampling times. The integral represents a measure of the total fraction of cells showing aberrations and the total amount of aberrations induced in the irradiated cell population. In addition, a correction factor is applied which takes into account the dilution of heavily damaged cells at late sampling times by cell division of undamaged or less severely damaged cells.

RESULTS AND CONCLUSIONS

Previously published data on the induction of chromosome aberrations by 4.6 MeV/u Ar ions and X-rays are re-analysed using the new approach. It is demonstrated that this method allows a better comparison of experiments using extremely different radiation qualities and consequently different cell cycle perturbations.

Particle-induced chromosome aberrations and mutations: an overview

Energy depositions by sparsely and densely ionizing radiation in the cellular DNA are responsible for deleterious radiobiological effects like the induction of chromosome aberrations or gene mutations. However, due to differences in the spatial pattern of energy deposition the action of densely ionizing radiation is quantitatively and qualitatively different from that of sparsely ionizing radiation. By the use of new molecular-biological techniques a deeper insight into the molecular events underlaying particle-induced genetic changes has been obtained. The present paper will attempt to give a brief overview of progress in chromosome and mutation studies, Furthermore, recent published data on delayed genetic effects of cellular exposure to ionizing radiation will be summarized.

Manganese superoxide dismutase (MnSOD) and autoantibodies against MnSOD in acute viral infections

Sera of 146 patients with acute EBV, HAV, HBV, CMV, HSV, and rubella virus infections, and sera from 35 healthy controls were tested for the antioxidant enzyme manganese superoxide dismutase (MnSOD). An enzyme immunoassay that detects all isomeres of the enzyme was developed. The mean MnSOD value of healthy controls was 107 ng/ml. In HAV, HBV and EBV infections characterized by viral replication in internal organs, there was an average 5-fold rise of serum MnSOD, whereas in viral infections with low direct cytopathogenity, such as rubella, CMV and HSV, the MnSOD levels showed only minor rises. These sera were also tested for autoantibodies against MnSOD using a novel sensitive indirect enzyme immunoassay. The average IgM anti-MnSOD concentration in sera of healthy controls was 112 GU. In sera of patients with acute HBV, CMV, HSV or rubella virus infections IgM anti-MnSOD values were only slightly raised above the cut-off level. In contrast, in some patients with acute EBV infections anti-MnSOD concentrations rose up to 20-fold of normal values. In HAV infections the same phenomenon was observed in patients who had reactivated EBV infections. These findings indicate that EBV may facilitate the B-cell response to MnSOD. These autoantibodies may inhibit the protective function of MnSOD and prolong the disease by oxygen injury. Our concept on the pathogenic effect of the autoantibodies against MnSOD emphasizes the importance of the antioxidant enzyme in viral infections.

Bladder control a consequence of maturation: evidence after renal transplantation

This report contains case studies on three children with early end-stage renal failure due to renal malformation or nephrotic syndrome, but without bladder involvement. All patients became anuric in the second year of life, before having obtained bladder control. They underwent successful cadaveric renal transplantation, having been anuric for almost 2 to 4 years. When the bladder catheter was removed 5 days after transplantation, all three children asked for the urine potty without ever having been prompted. Three weeks after transplantation, all three children achieved complete bladder control during the day, and two of them also at night. These observations add further evidence to the notion that the development of bladder control is a consequence of maturation and not of training.

Galanin injection into the nucleus of the solitary tract stimulates feeding in rats with lesions of the paraventricular nucleus of the hypothalamus

Feeding can be stimulated by injection of galanin into the area postrema/nucleus of the solitary tract (AP/NTS) or fourth ventricle (4V). However, the threshold for galanin-induced feeding is lower when galanin is injected into the paraventricular nucleus of the hypothalamus (PVN) than when injected into the NTS. The greater apparent sensitivity of the PVN to galanin and the proximity of this nucleus to the third ventricle raise the possibility that galanin injected into the AP/NTS or 4V may stimulate feeding by accessing receptors in the PVN rather than by a local action in the hindbrain. To assess this possibility, feeding in response to NTS galanin was evaluated in rats with bilateral electrolytic lesions of the PVN. We found that PVN lesions did not abolish feeding induced by injections of galanin into the NTS. Rather, galanin-induced feeding, but not mercaptoacetate- or 2-deoxy-D-glucose-induced feeding, was significantly enhanced in PVN-lesioned rats compared to sham-operated controls. These results suggest that galanin receptors in the NTS region mediate feeding in response to galanin and that the galaninergic nerve terminals innervating these receptors may originate in part from cell bodies in the PVN.

Induction of chromosomal damage in CHO-K1 cells and their repair-deficient mutant XRS5 by X-ray and particle irradiation

The cytogenetic effects of X-rays and Au ions were investigated in repair-proficient CHO-K1 cells and their radiosensitive mutant strain xrs5, which shows a defect in the rejoining of DNA double-strand breaks. Both cell lines were synchronized by mitotic shake off, irradiated in G1-phase with either 250 kV X-rays or 780 MeV/u Au ions (LET: 1150 keV/micrometer) and chromosome aberrations were analyzed in first post-irradiation metaphases. Isoeffective doses of X-rays for the induction of aberrant cells and aberrations per cell were about 14 times lower for xrs5 than for CHO-K1 cells. After high LET radiation the difference in the cytogenetic response of both cell lines was drastically diminished. Furthermore, the analysis of the aberration types induced by sparsely and densely ionizing radiation showed for both cell lines specific changes in the spectrum of aberration types as LET increases. The experimental results are discussed with respect to the different types of lesions induced by sparsely and densely ionizing radiation.

Comparison of sperm viability with seminal plasma metal levels

This study compares the semen levels of lead (Pb), cadmium (Cd), and aluminum (Al) in relation to live sperm in semen samples from 64 apparently healthy men. The measured levels were separated into live sperm count tertiles (<25% [18 subjects], 25-50% [26 subjects], and >50% [20 subjects]). The mean +/- SD for each group was calculated, and the difference between the means of the high and low tertiles were compared by ANOVA. Significant differences were observed between the high and low live sperm groups for Pb (p < 0.01) and Al (p < 0.05), but not Cd. Spearman's rank correlation between sperm viability and the semen plasma metal levels showed a direct relation to Mg (p < 0.05). However, there was an inverse relation to lead (p < 0.001), cadmium (p < 0.01), and aluminum (p < 0.01). There was no significant correlation between Ca and Zn. Linear regression between the live sperm counts and semen level of the three metals show that metal levels were inversely correlated with the percentage of live sperm (p < 0.001, < 0.01). Apparently, the presence of these metals in the environment and in seminal plasma exerts a toxic effect on sperm.